Advances in Cardiovascular Magnetic Resonance in Ischaemic Heart Disease and Non-ischaemic Cardiomyopathies | Ten Points to Remember

Motwani M, Kidambi A, Greenwood JP, Plein S.
Heart 2014;100:1722-1733.
The following are 10 points to remember about advances in cardiovascular magnetic resonance (CMR) in ischaemic heart disease and nonischemic cardiomyopathies:

1. Evidence for the role of CMR imaging is now incorporated into expert consensus statements and appropriate use criteria from the American College of Cardiology (ACC), American Heart Association (AHA), American College of Radiology (ACR), European Society of Cardiology (ESC), and Society of Magnetic Resonance (SCMR).

2. Stress perfusion CMR imaging has higher sensitivity and diagnostic accuracy than nonattenuation corrected single-photon emission computed tomography (SPECT). Furthermore, a negative stress CMR study carries an extremely favorable prognosis.

3. Stress perfusion CMR now carries a Class I recommendation in intermediate-risk patients with suspected angina in 2013 ESC guidelines, and a Class IIa recommendation in 2012 ACC/AHA guidelines.

4. Emerging techniques will further improve spatial resolution of stress CMR (which already exceeds nuclear techniques), and will improve whole heart coverage. The advantages of these improvements include reduced artifacts and increased sensitivity for small amounts of subendocardial ischemia.

5. In the post-infarct setting, CMR is able to accurately quantify chamber volumes and function, infarct extent and transmurality, area at risk, microvascular obstruction, and intramyocardial hemorrhage. These parameters can be useful for overall risk stratification and for assessment of likelihood of functional recovery with revascularization. Late gadolinium enhancement (LGE) imaging can also assist in cases of myocardial infarction with apparently normal coronary arteries, differentiating stress-induced cardiomyopathy from myocarditis and missed myocardial infarctions due to nonocclusive plaques.

6. Although not yet evaluated prospectively, the absence of scar on LGE imaging may be helpful for identification of patients likely to benefit from implantable cardioverter-defibrillator therapy. Specifically, among those with reduced left ventricular ejection fraction (LVEF) (≤30%), those without significant scar (<5% of the LV) had a generally favorable prognosis (comparable to those with preserved LVEF).

7. In dilated cardiomyopathy, multiple studies have demonstrated the prognostic importance of fibrosis, as detected by LGE imaging.

8. In hypertrophic cardiomyopathy, CMR may be used to quantify the extent and severity of hypertrophy and to identify and quantify fibrosis, which is a strong predictor of sudden cardiac death.

9. CMR imaging with LGE is twice as sensitive as standard clinical criteria for diagnosis of cardiac involvement in sarcoidosis. The presence of LGE is associated with a 12-fold increase in cardiac death.

10. Emerging quantitative mapping techniques for myocardial T1 will allow quantification of diffuse fibrosis in diseases such as hypertrophic cardiomyopathy, aortic stenosis, and cardiac amyloidosis.
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